Motor drive control including varying DC bus voltages, converter and inverter switching frequencies, and motor speed for thermal mitigation
In other features, a refrigeration system is provided and includes a compressor motor, an inverter, a converter and a control module. The inverter is configured to convert a direct current (DC) bus voltage to an alternating current (AC) voltage and supply the AC voltage to the compressor motor. The converter is configured to convert a DC input voltage to the DC bus voltage. The control module is configured to obtain a parameter and in response to the parameter exceeding a predetermined threshold, reduce the DC bus voltage and at least one of (i) reduce a switching frequency, (ii) increase an amount of negative d-axis current of the compressor motor, or (iii) reduce a speed of the compressor motor.
1 . A refrigeration system, comprising:
a compressor motor;
an inverter configured to convert a direct current (DC) bus voltage to an alternating current (AC) voltage and supply the AC voltage to the compressor motor;
a converter configured to convert a DC input voltage to the DC bus voltage; and
a control module configured to obtain a parameter and in response to the parameter exceeding a predetermined threshold, reduce the DC bus voltage and increase an amount of negative d-axis current of the compressor motor.
2 . The refrigeration system of claim 1 , wherein the parameter is a temperature or a current level of current supplied to the compressor motor.
3 . The refrigeration system of claim 1 , wherein:
the control module is configured to obtain the parameter and one or more other parameters and in response to the parameter and the one or more other parameters, reduce the DC bus voltage and at least one of (i) reduce a switching frequency, (ii) increase the amount of negative d-axis current of the compressor motor, or (iii) reduce a speed of the compressor motor to a speed greater than zero;
the parameter is a temperature; and
the one or more other parameters include a current level of current supplied to the compressor motor.
4 . The refrigeration system of claim 1 , wherein:
the control module is configured to, based on the parameter, reduce a switching frequency of the converter; and
the control module is configured to, in response to the parameter exceeding the predetermined threshold, reduce the switching frequency of the converter.
5 . The refrigeration system of claim 4 , wherein the control module is configured to, in response to the parameter exceeding the predetermined threshold and in addition to reducing the switching frequency of the converter, also reduce the switching frequency of the inverter.
6 . The refrigeration system of claim 1 , wherein:
the control module is configured to, based on the parameter, reduce a switching frequency of the inverter; and
the control module is configured to, in response to the parameter exceeding the predetermined threshold, reduce the switching frequency of the inverter.
7 . The refrigeration system of claim 1 , wherein the control module is configured to
obtain a temperature of the converter; and
in response to the temperature of the converter being greater than a predetermined temperature, reduce the DC bus voltage and at least one of (i) reduce a switching frequency of the inverter, or (ii) reduce a switching frequency of the converter.
8 . The refrigeration system of claim 7 , wherein the control module is configured to, subsequent to reducing the DC bus voltage and the at least one of (i) reducing a switching frequency of the inverter, or (ii) reducing a switching frequency of the converter, and in response to the temperature of the converter not increasing and/or not increasing at a predetermined rate, reduce a speed of the compressor motor to a speed greater than zero.
9 . The refrigeration system of claim 1 , wherein:
the parameter is a temperature of the converter; and
the control module is configured to, in response to the temperature of the converter being greater than a predetermined temperature, increase the amount of negative d-axis current of the compressor motor.
10 . The refrigeration system of claim 9 , wherein the control module is configured to decrease a speed of the compressor motor to reduce the temperature of the converter, only subsequent to determining that reduction in switching frequency of the converter and reduction in the DC bus voltage is not at least one of (i) reducing the temperature of the converter, or (ii) reducing the temperature of the converter at least at a predetermined rate.
11 . The refrigeration system of claim 1 , wherein the control module is configured to reduce a speed of the compressor motor to a speed greater than zero in response to the parameter exceeding the predetermined threshold.
12 . The refrigeration system of claim 1 , wherein the control module is configured to:
obtain a temperature of the converter, a temperature of the inverter, a temperature of the control module, and an ambient temperature; and
based on the temperature of the converter, the temperature of the inverter, the temperature of the control module, and the ambient temperature reduce the DC bus voltage and at least one of (i) reduce a switching frequency of the inverter, or (ii) reduce a switching frequency of the converter.
13 . The refrigeration system of claim 12 , wherein the control module is configured to:
determine which one of the temperature of the converter, the temperature of the inverter, the temperature of the control module, and the ambient temperature is a lowest temperature; and
reduce the switching frequency based on the lowest temperature.
14 . The refrigeration system of claim 12 , wherein the control module is configured to:
determine which one of the temperature of the converter, the temperature of the inverter, the temperature of the control module, and the ambient temperature is a lowest temperature; and
reduce a speed of the compressor motor to a speed greater than zero based on the lowest temperature.
15 . The refrigeration system of claim 12 , wherein the control module is configured to:
determine which one of the temperature of the converter, the temperature of the inverter, the temperature of the control module, and the ambient temperature is a lowest temperature; and
reduce the DC bus voltage based on the lowest temperature.
16 . The refrigeration system of claim 1 , further comprising a sensor configured to detect the parameter.
17 . The refrigeration system of claim 1 , wherein:
the parameter is a temperature of the converter;
the converter is a DC-to-DC boost converter; and
the control module is configured to
based on the parameter, reduce a switching frequency of a switch of the converter,
obtain the temperature of the converter and an ambient temperature, and
in response to (i) the temperature of the converter exceeding the predetermined threshold, and (ii) the ambient temperature being within a first predetermined temperature range, reduce the switching frequency from a first switching frequency to a second switching frequency and reduce the DC bus voltage from a first DC bus voltage to a second DC bus voltage.
18 . The refrigeration system of claim 17 , wherein the control module is configured to, in response to the temperature of the converter being greater than the predetermined threshold and the ambient temperature being within a second predetermined temperature range that is different than the first predetermined temperature range, further reduce the switching frequency from the second switching frequency to a third switching frequency and further reduce the DC bus voltage from the second DC bus voltage to a third DC bus voltage.
19 . The refrigeration system of claim 1 , wherein the control module is configured to control the inverter in at least one of an overmodulation state or a clamping state to reduce the parameter.
20 . The refrigeration system of claim 1 , wherein the control module is configured to control the inverter in an overmodulation state and a clamping state to reduce the parameter.
21 . The refrigeration system of claim 1 , wherein the control module is configured, in response to the parameter exceeding the predetermined threshold, to reduce the DC bus voltage, reduce a switching frequency, and reduce a speed of the compressor motor to a speed greater than zero.
22 . A refrigeration system, comprising:
a compressor motor;
an inverter configured to convert a direct current (DC) bus voltage to an alternating current (AC) voltage and supply the AC voltage to the compressor motor;
a converter configured to convert a DC input voltage to the DC bus voltage; and
a control module configured to
obtain at least one of a temperature of the control module or an ambient temperature; and
based on the at least one of the temperature of the control module or the ambient temperature, reduce the DC bus voltage and at least one of (i) reduce a switching frequency of the inverter, or (ii) reduce a switching frequency of the converter.
23 . A method of operating a refrigeration system, comprising:
convert via a converter a direct current (DC) input voltage to a DC bus voltage, wherein the converter is a DC-to-DC boost converter;
converting the DC bus voltage to an alternating current (AC) voltage and supplying the AC voltage to drive a compressor motor;
detecting a temperature of the converter;
obtaining an ambient temperature; and
in response to (i) the temperature of the converter exceeding a predetermined threshold, and (ii) the ambient temperature being within a first predetermined temperature range, reducing a switching frequency from a first switching frequency to a second switching frequency and reducing the DC bus voltage from a first DC bus voltage to a second DC bus voltage, wherein the switching frequency is a switching frequency of a switch of the converter.
24 . The method of claim 23 , further comprising, in response to the temperature of the converter being greater than the predetermined threshold and the ambient temperature being within a second predetermined temperature range that is different than the first predetermined temperature range, further reducing the switching frequency from the second switching frequency to a third switching frequency and further reducing the DC bus voltage from the second DC bus voltage to a third DC bus voltage.
25 . The refrigeration system of claim 22 , wherein the control module is configured to:
obtain the temperature of the control module and the ambient temperature; and
based on the temperature of the control module and the ambient temperature, reduce the DC bus voltage and at least one of (i) reduce a switching frequency of the inverter, or (ii) reduce a switching frequency of the converter.
26 . A refrigeration system, comprising:
a compressor motor;
an inverter configured to convert a direct current (DC) bus voltage to an alternating current (AC) voltage and supply the AC voltage to the compressor motor;
a converter configured to convert a DC input voltage to the DC bus voltage; and
a control module configured to
obtain at least one of a temperature of the inverter, a temperature of the control module, or an ambient temperature; and
based on the at least one of the temperature of the inverter, the temperature of the control module, or the ambient temperature, reduce the DC bus voltage and reduce a switching frequency of the converter.
27 . The refrigeration system of claim 26 , wherein the control module is configured to, based on the at least one of the temperature of the inverter, the temperature of the control module, and the ambient temperature, reduce the DC bus voltage and reduce a switching frequency of the converter.