Control method of a hybrid power switch
A control method of a hybrid power switch having at least a first switching device connected in parallel with a second switching device is provided. A first gate signal is provided to the first switching device for turning on and turning off the first switching device. A second gate signal is provided to the second switching device for turning on and turning off the second switching device. A first delay time is stablished between the turning on of the first switching device and the turning on of the second switching device, and a second delay time is established between the turning off of the first switching device and the turning off of the second switching device. The temperature of the first switching device is determined, and at least one of the first and second delay times is modified depending on such temperature.
1. A control method of a hybrid power switch having at least a first switching device connected in parallel with a second switching device, wherein switching losses of the first switching device are lower than switching losses of the second switching device for same current and voltage conditions, the method comprising:
providing a first gate signal to the first switching device of the hybrid power switch for turning on and turning off the first switching device;
providing a second gate signal to the second switching device of the hybrid power switch for turning on and turning off the second switching device, establishing a first delay time between the turning on of the first switching device and the turning on of the second switching device;
establishing a second delay time between the turning off of the first switching device and the turning off of the second switching device;
determining a temperature of the first switching device of the hybrid power switch;
modifying at least one of the first delay time and the second delay time depending on the temperature of the first switching device;
comparing the temperature with a reference curve which defines a relationship between temperatures of the first switching device and percentage values for modifying the at least one of first delay time and the second delay time;
obtaining a percentage value according to the temperature using the reference curve; and
applying the percentage value to the at least one of first delay time and the second delay time so as to modify the at least one of first delay time and the second delay time,
wherein the reference curve is established between three junction temperatures of the first switching device, and wherein below a first junction temperature the reference curve is lineal and takes a constant value, from the first junction temperature to a second junction temperature the reference curve decreases linearly, and from the second junction temperature to a third junction temperature the reference curve further decreases linearly.
2. The method according to claim 1 , wherein the modifying at least one of the first delay time and the second delay time comprises:
delaying the turning on of the first switching device thereby reducing the first delay time.
3. The method according to claim 1 , wherein the modifying the at least one of the first delay time and the second delay time comprises:
advancing the turning off of the first switching device thereby reducing the second delay time.
4. The method according to claim 1 , wherein the modifying the at least one of the first delay time and the second delay time comprises:
delaying the turning on of the first switching device thereby reducing the first delay time; and
advancing the turning off of the first switching device thereby reducing the second delay time.
5. The method according to claim 1 , wherein below the first junction temperature the reference curve has a constant percentage value of 100%, at the second junction temperature the reference curve has a percentage value of zero, and at the third junction temperature the reference curve has a negative percentage value.
6. The method according to claim 1 , further comprising:
multiplying the percentage value for modifying the first delay time with a turning-on weight factor, and
multiplying the percentage value for modifying the second delay time with a turning-off weight factor,
wherein turning-on and turning-off weight factors have a predefined value between 0 and 1.
7. The method according to claim 1 , wherein the first switching device is turned on before the second switching device.
8. The method according to claim 1 , wherein the first switching device is turned on after the second switching device.
9. The method according to claim 1 , wherein the first switching device is turned off after the second switching device.
10. The method according to claim 1 , wherein the first switching device is wide band gap switch.