Inverter driving circuit an inverter control circuit
View Patent ↗A phase adjusting circuit is provided that is capable of adjusting a delay time at a rise or fall of a driving signal for driving an inverter. A phase adjusting circuit is provided upstream of a driver circuit, and an output from a hysteresis comparator is input to the driver circuit through the phase adjusting circuit. The phase adjusting circuit delays at least either rise or fall of the signal input to the driver circuit to adjust any difference between the pulse width of the input signal input to the driver circuit and the pulse width of a signal output from a switching element of an inverter driven by the driver circuit.
1. An inverter driving circuit comprising:
an input circuit for inputting an input signal in the form of a rectangular wave;
a driver circuit for driving an inverter based on the input signal input through the input circuit; and
a phase adjusting circuit which is provided upstream of the driver circuit and which delays at least either a rise or a fall of the input signal to adjust any difference between a pulse width of the input signal input to the driver circuit and a pulse width of a signal output from a switching element of the inverter driven by the driver circuit;
wherein the phase adjusting circuit adjusts the delay time of at least either the rise or the fall of the input signal such that a delay time between a point when the input of the input signal to the driver circuit is started and a point when the switching element is turned on equals a delay time between a point when the input of the input signal to the driver circuit is stopped and a point when the switching element is turned off.
2. The inverter driving circuit according to claim 1 , wherein the phase adjusting circuit includes:
a constant current source for generating a constant current;
a capacitor for charging the current generated by the constant current source;
a reference voltage source for generating a reference voltage;
a switching element for supplying the current generated by the constant current source to the capacitor based on the input signal; and
a comparator for comparing the reference voltage generated by the reference voltage source and a voltage generated by the capacitor and wherein the delay time of at least either rise or fall of the input signal is set based on the result of the comparison made by the comparator.
3. The inverter driving circuit according to claim 2 , wherein at least one of the constant current source, the capacitor, and the reference voltage source includes a plurality of such elements having different current values, capacities or reference voltages and wherein any of the constant current sources, capacitors or reference voltage sources is selected from the plurality of constant current sources, capacitors or reference voltage sources to adjust at least either the rise or the fall of the input signal.
4. The inverter driving circuit according to claim 2 , wherein at least one of the constant current source, the capacitor, and the reference voltage source is incorporated through an external terminal of the driving circuit.
5. An inverter control circuit, comprising:
a PWM control unit for exercising PWM control over an inverter; and
a phase adjusting circuit which is provided upstream of a driving circuit for driving the inverter and which delays at least either a rise or a fall of a control signal output from the PWM control unit to adjust a difference between a pulse width of an input signal input to the driving circuit and a pulse width of a signal output from a switching element of the inverter controlled by the driving circuit
wherein the phase adjusting circuit adjusts the delay time of at least either the rise or the fall of the control signal such that a delay time between a point when the input of the input signal to the driver circuit is started and a point when the switching element is turned on equals a delay time between a point when the input of the input signal to the driver circuit is stopped and a point when the switching element is turned off.
6. The inverter control circuit according to claim 5 , wherein the phase adjusting circuit includes:
a constant current source for generating a constant current,
a capacitor for charging the current generated by the constant current source,
a reference voltage source for generating a reference voltage,
a switching element for supplying the current generated by the constant current source to the capacitor based on the input signal, and
a comparator for comparing the reference voltage generated by the reference voltage source and a voltage generated by the capacitor and wherein the a delay time of at least either rise or fall of the control signal is set based on the result of the comparison made by the comparator.
7. The inverter control circuit according to claim 6 , wherein at least one of the constant current source, the capacitor, and the reference voltage source is constituted by a plurality of such elements having different current values, capacities or reference voltages and wherein any of the constant current sources, capacitors or reference voltage sources is selected from the plurality of constant current sources, capacitors or reference voltage sources to adjust at least either rise or fall of the control signal.
8. The inverter control circuit according to claim 6 , wherein at least one of the constant current source, the capacitor, and the reference voltage source is incorporated through an external terminal of the control circuit.